Rachel and Na Young

The Changes in the Voltage of Battery
Abstract:


For this investigation, we used four beakers with same amount of water in and with different concentration of salt for each beaker to find if there are any differences in voltage. However, we discovered something that is out of our expectation and saw a difference in the color and the amount of voltage after leaving two beakers for three days. We in the end discovered that there is no real difference in voltage for each concentration we tried.

Introduction:

Purpose:
The purpose of our experiment is to find out whether the differences in concentration of salt will affect the voltage of the battery.

Dependent variable: The voltage of the battery

Independent variable: The Concentration of salt


Expectations: We expected that the voltage will increase if the salt water in the beaker increases in its concentration of salt. We had this assumption, because we thought the battery will be affected by the concentration of liquid involved.





Procedure:


Materials:
l 4 Beakers (250mL)
l Digital Balance
l Plastic Cup
l 4 Coppers
l 4 Aluminums
l Water (100mL for each beaker)
l Salt
l Stirring stick
l Wires
(first beaker: 113.46g, second beaker: 108.77g, third beaker: 112.38g, fourth beaker: 105.93g)





Step1: Use the digital balance to weight the plastic cup (3.33g)

Step 2: Use the digital balance to weight each of the beakers that is labeled in numbers
Step3: Put 10grams of salt in the empty plastic cup


Step 4: Fill in the empty “#1 beaker” with 100mL of water.

Step 5: Put the 10grams of salt inside the beaker and stir it until the salt are invisible


Step 6: Place in one copper and aluminum in the beaker and use the wires to clip on the metals.

Step 7: Measure the amount of voltage and wait for 30 seconds for a little more accurate number.

Step 8: Continue the same steps from step 1 to step 7, but by measuring 7.5grams of salt for the second beaker, 5grams for the third beaker and 2.5grams for the last beaker.


Expected Graph:


Labeled Sketch:



Data:



First Experiment:
#1 Beaker: 113.46gram
Salt: 10gram
Voltage: 0.53 (+/- 0.02)

Second Experiment:
#2 Beaker: 108.77gram
Salt: 7.5gram
Voltage: 0.55 (+/- 0.01)

Third Experiment:
#3 Beaker: 112.38gram
Voltage: 0.53 (+/-0.005)

Fourth Experiment:
#4 Beaker: 105.93gram
Voltage: 0.55 (+/-0.005)




Actual graph and data:



Unexpected Observations:
Our experiment was divided into two days, we tested the first two beakers for the first day and the other two on the second day. We let the first two beakers sat for 3 days, and found something unusual about it. The first beaker: liquid that were soaked with metals, 100g of water and 10g of salt had a foggy white color, and there are bubbles around the metals. It doesn't come off even though we shook it. The liquid between the space of the metals is milky white, and there are no solid salt in the bottom of the beaker. Its voltage decreased from 0.538 (+/-0.05) to 0.51(+/-0.02) and it doesn't the voltage doen't change rapidly like it is before. Second beaker: It color is foggy aqua colored and it has left over aqua color salt in the bottom of the beaker, the batteries voltage was 0.55(+/-0.05) but now it is 0.502(+/-0.05), and it also doesn't change rapidly.


Evaluations:
(Rachel's)
(Na Young's)